522 ACCOUNT OP ASTRONOMICAL OBSERVATIONS 



sector, (Table V.) gives the latitude of the Observa- 

 tory only 13° 4' 3''.328 which is less by 10''.326 than 

 that brought out by the stars in Table II. 



23. The great difficulty'of observing the sun, when 

 in the meredian in tropical climates, owing to the great 

 tremor of the atmosphere ar noon time, induced me not 

 to consult it in laying down the latitude of this Obser* 

 vatorv. 



24. Flow EVER, on comparing the mean latitude in 

 Table V. with the result of similar observations, for- 

 merly taken with the same instrument by Mr. Gold- 

 iNGHAM, (56 in number) I found that his latitude by 

 the sun, namely, 13° 4' 5''.66, differed only by 2".332 

 from mine. There could therefore remain no doubt 

 that the sun gave a lower latitude than the stars ; and 

 I was further confirmed in this opinion, on Major 

 Lambton communicating to me his remark, that when 

 observing the sun, in various parts of the Peninsula, 

 his results were likewise in defect. 



25. In order to make a further trial of this, let us 

 compute the exact time when the sun was precisely in 

 the parallel of the Madras Observatory, and then (taking 

 the difference of longitude between Greenwich and this 

 place to be well known) determine the sun's declination 

 for that moment, from what it is given in the nautical 

 almanac for two preceding, and two succeeding moons. 



26. For this, taking the four zenith distances ob- 

 served nearest and on each side of the zenith, and in- 

 terpolating in the usual way *, we have 



• The formula of which is y ^z. a \ P x Q. x — ^+ it x -^ 

 '^^ &c. where x is to be found by resolving the equation. 



